EASA Module 7 common mistakes
EASA Module 7 · Understand the traps and how to avoid them.
Classifies a fit designation such as H7/g6 by the alphabet ('g comes after H, so it must be interference') or adds the allowance with the wrong sign when calculating maximum and minimum clearance.
The letter-number codes get memorised as labels rather than as fundamental deviations lying on one side or the other of the zero line, so the candidate names the fit instead of computing it.
What to do instead
Sketch the zero line on the answer sheet every time. Capital letters are holes, lower-case are shafts; H has its lower deviation at zero, h has its upper deviation at zero. Then compute hole limits and shaft limits numerically and compare: if the shaft's upper limit is below the hole's lower limit it is a clearance fit, regardless of the letters.
Routes a replacement wire bundle alongside a hydraulic or fuel pipe and secures both with the same P-clamp to save space, or uses a cable tie to hang a bundle from another loom.
Loom routing is treated as a packaging problem ('it fits, so it is fine') rather than as a separation and support requirement.
What to do instead
EWIS must be routed and clamped separately from fluid lines, Oxygen lines and structure. Use approved stand-offs and clamps at the specified intervals, keep the specified clearance and bend radius, fit drip loops at penetrations into pressurised or wet areas, and never use a wire, bundle or tie as a structural support for anything.
Selects a solid rivet by shank diameter alone, or takes the rivet 'length' as the total thickness of the sheets being joined.
The part number's last digits (e.g. MS20470AD4-6) are read as an overall length, when the dash number is the grip length in sixteenths of an inch, and the installed length must also form a driven head.
What to do instead
Grip = total thickness of the stack (plus any sealant or interlayer allowance). Installed rivet length ≈ grip + 1.5 × shank diameter for a universal head. Confirm with the rivet gauge, drill and deburr the correct hole size, and check the finished driven head diameter and height against the standard before moving on.
Applies the manual torque figure unchanged when a crowfoot or an extension is fitted in line with the wrench handle, and uses the same torque wrench to crack loose a seized nut.
Torque is treated as a property of the fastener rather than of the wrench geometry and of the friction in the threads and under the head.
What to do instead
A crowfoot at 90° to the wrench needs no correction; an adapter in line with the handle changes the effective lever length and requires recalculation (adjusted = indicated × wrench length ÷ (wrench length + adapter length)). Never use a torque wrench to loosen, wind it back to zero after use, check calibration, and apply the dry, lubricated or wet condition stated in the manual.
Reads a first-angle drawing using third-angle conventions and therefore puts the machined feature or hole pattern on the wrong face, or works from a dimension without checking the revision block.
Almost all training examples and textbook illustrations are third angle; the two systems use the identical three views and differ only in how they are arranged around the front view.
What to do instead
Find the projection symbol by the title block (the truncated cone). In third angle the view is placed on the same side as the direction of viewing, so the top view sits above the front view; in first angle the top view sits below. Also confirm revision status, units and whether dimensions are toleranced or basic before using any number.
Fuels or defuels an aircraft without first bonding it to earth, or carries a grease-contaminated tool or a roll of PTFE tape to an oxygen system.
Static and oxygen-enrichment hazards are invisible, so bonding and cleanliness read as paperwork rather than as the primary defence.
What to do instead
Connect the earth-to-aircraft bond before hose connection and keep it on until caps and panels are closed. For oxygen: only oxygen-clean equipment, no oil, grease, PTFE tape or non-approved lubricants, and no smoking or open flame in the area. Treat every fuel or oxygen task as a permit-controlled task with the PPE and gas testing it specifies.
Feeds a station ahead of the datum into the moment table as a positive arm, or mixes inches and feet, or pounds and kilograms, within the same calculation.
The moment formula is simple, so it is executed by habit, and the sign of the arm is decided as an afterthought rather than written down before multiplying.
What to do instead
Convert every figure to the units of the CG limits table first, then write each arm with its sign (negative forward of the datum) before multiplying. Sanity-check the result: total moment ÷ total weight must lie inside the envelope and close to the published empty-weight CG; an answer metres out is a sign error, not a rounding error.
States that brazing melts the parent metal, or describes a filler flowing at around 600 °C as soldering.
All three processes join metal using heat and a filler, and only the melting behaviour of the parent metal and the filler's temperature band distinguish them.
What to do instead
Soldering uses a filler melting below 450 °C, brazing above 450 °C, and in both the parent metal remains solid; only welding melts the parent. Remember also the practical limits: no soft soldering on primary structure or on wiring in high-vibration or high-temperature zones where a specified splice or terminal is required.
Strips a component and puts bolts, washers, shims and cap plugs into one tray, then reassembles from memory or from the illustrated parts catalogue alone.
Time pressure plus the assumption that hardware is interchangeable and that an exploded parts view contains the shim thicknesses, rigging data and torque values.
What to do instead
Tag and bag hardware by location, record shim packs and washer positions before removal, and cap or plug every open line, hose and connector immediately. Reassemble strictly to the maintenance manual procedures and torque schedule, and record the as-fitted condition so the next person can see what was done.
Runs lockwire so that a loosening fastener pulls the wire taut in the loosening direction, finishes with a long straight pigtail that can be hooked, or twists the wire with pliers instead of the approved twister.
The aim is remembered as 'wire the bolt so it cannot turn' without the direction rule, and pliers feel quicker than finding the twister.
What to do instead
Route the wire diagonally so that any tendency to loosen pulls the wire in the tightening direction, with 6–8 twists per inch, a 3–6 mm pigtail bent over and down and clear of edges and servicing points. Use the correct twister and wire gauge, protect against sharp edges, and never reuse a wire that has already been twisted.